For many years the digital health industry has been driven by wearable devices like the Fitbit, Nike’s Fuelband, and Jawbone’s Up. But if the titans of the smartphone industry succeed in creating a dominant platform for health and fitness data, this business could be in trouble. “A lot of the basic functions we have seen in fitness wearables — tracking your steps, taking your heart rate — those functions will become basic features on a smartphone or smartwatch,” says Wang.
As someone who’s worn one of these trackers for years now  and who is obsessive about carrying my smartphone, I cannot disagree more. My phone does rough calculation of how much I move every month and it’s routinely off by absolutely enormous magnitudes.  To some extent, that’s because the phone isn’t calibrated to precisely monitor how far I walk. To a greater extent, however, it’s because while I’m obsessive about keeping my phone around me it’s actually not on my person for about 30% of my movements each day. I don’t carry my phone at night when walking the dog, or necessarily when I’m wander around the building I work in.
For people who want just casual or ambient information about movement a smartphone might be fine. But anyone who is even moderately interested in tracking their activity for health reasons isn’t going to be willing to ‘guesstimate’ 1/3 of their day’s activity. The real power of smartphones is delivering information-rich notifications or aggregating data from a variety of sensors; it’s the software that they bring, first and foremost, that is their value add. And I think that for the fitness device companies to be successful they’ll need to develop powerful data mobilization schemes – you’ll need to be able to integrate data from the fitness hardware to any smartphone OS – to really capture significant portions of the market over the longer-term. I don’t buy the idea that people will keep buying sub-par products because the data is bound within a specific operating system or mobile phone ecosystem. Though, perhaps that’s just me as someone who hops between smartphone and smartphone OSes every 12–14 months.